Cloning Of Calcineurin B-Like (CBL) Genes In Wheat (Triticum Aestivum L.) And Function Analysis Of TaCBL1

Wheat is one of staple crops worldwide. Various natural disasters, such as drought, floods, salinization and other dramatic changes of environment, as well as insect pests, resullt in wheat yield loss. Therefore, improving tolerance to these stresses is very important to ensure wheat production.In plant, various stimuli from environment changes lead to the changes of Ca²⁺ concentration within the cell to relay the signals. Acorrding to these signals, plant will adjust their physiological and biochemical processes so as to adapt them to survive the harsh environment. As Ca²⁺ sensors, Ca²⁺-binding protein families play important roles in signal transduction and stress resistance of plants. Until now, calcium binding proteins found in plants are devided into three main categories, calmodulin?CaM? and CaM-like proteins, calcium-dependent protein kinases?CDPK? and calcineurin B-like protein?CBL?.In this thesis, TaCBL gene sequences were obtained. The expression profile and the subcelluar localalization of TaCBLs were studied, and TaCBL1 was transformed into tobacco and functionally characterzed. The main results are as follows.?1? EST sequences obtained from databases were assembled into 11 unigenes through bioinformatic technique, and c DNAs of three CBL genes containing the whole ORF?Open Reading Frame? were cloned and designated as TaCBL1, TaCBL3 and TaCBL6 respectively, The structure analysis of TaCBL proteins showed their highly similarity with coresponding CBLs in Arabidopsis, rice, poplar, maize.?2? The results of q RT-PCR?Real-time Quantitative PCR? revealed the expression patterns of TaCBL1, TaCBL3 and TaCBL6 in various organs at different stages, as well as the expression changes in seedlings treated with low tamperatue, drought, salinity and ABA respectively. The results showed that one TaCBL might function in responses to multiple stresses, and one stress can induce multiple TaCBLs expression changes.?3? Three fusion-protein expression vectors, TaCBL1-GFP, TaCBL3-GFP and TaCBL6-GFP were constructed and transferred into onion epidermal cells respectively. Observed with fluorescence microscope and we found that TaCBL1-GFP, TaCBL3-GFP and TaCBL6-GFP protein can be detected at plasma membrane.?4? A TaCBL1-overexpression vector was constructed and transferred into tobacco?Nicotiana tabacum L. cv. Samsun? using the Agrobacterium-mediated transformation method. The stress-tolerance analysis of T2 generation of transgenic tobaccos showed that overexpressing TaCBL1 can enhance the drought tolerance of transgenic plants. In transgenic plants, the water contents were increased, cell damages were decreased, and the antioxidation abilities were enhanced.These results reveal that TaCBL1, TaCBL3 and TaCBL6 share significant characteristics with CBL protein family, and participate in stress signal transductions in wheat. The overexpressing TaCBL1 in plants enhanced drought stress tolerance through increasing antioxidant activities to resist to cell damage. These results help to research functions and signal pathways of CBL gene family, and indicate a new approach to improve wheat tolerance.